Conventional video conferencing equipment is generally divided into a number of categories. These categories include display and capture equipment, such as cameras, microphones, televisions and speakers, end point equipment that connects a particular video conference participant to another end point device or to a multi-point control unit, and the multi-point control unit, which allows three or more end point devices to participate in a single video conference session.
The end point equipment is used by participants in a video conference session to convert the audio and video signals from the camera and microphone into data transmittable to another end point device or the multi-point control unit. The end point equipment is also used to convert the transmitted audio and video signals, received at one end point from another end point or from the multi-point control unit, into signals usable by audio and video display devices connected to that end point to play the video and audio signals to the participants.
The multi-point control unit is a conference bridge that connects the various end points of a single video conference session together when more than two end point devices are to be involved in the video conference. In general, two end point devices can be connected directly to each other. In practice, most video conference sessions, even when only two participants are involved, are routed through a multi-point control device. In general, one multi-point control unit can be used for a number of video conference sessions, where each session has two or more participants. In operation, each of the end points contact the multi-point control unit. After data sufficient for the multi-point control unit to authenticate the participants' authorization to participate in a video conference session is provided to that multi-point control unit, the multi-point control unit connects that end point device to the one or more other end point devices, so that the user of that end point device can participate in that video conference session. The multi-point control unit, or a video conference administrator or coordinator, confirms a video conference participants' authorization to participate in the video conference session based on the video conference participant supplying a predefined password, or the like.
The H.320 standard is the standard for ISDN video conferencing. The H.323 standard extends the H.320 ISDN video conferencing standards to a standard usable for Internet protocol (IP)-based distributed networks. The Session Initiation Protocol (SIP) is a third video conferencing standard protocol. Video conference equipment, which uses the H.323 standard, uses standard Internet Protocol (IP) handshake and messaging protocols and data and packet formats that would be used on a standard Internet protocol (IP)-based distributed network, such as the Internet, many wide area networks and local area networks, intranets, extranets, and other distributed networks.
Porting the audio and video data signals of a video conference session to a distributed network, such as the Internet, for distribution as a multimedia data stream is known. Conventional video conference broadcasters re-encode the audio and video portions of the video conference through one of two techniques. One technique includes capturing the video portion of the video conference separately, by accessing the analog auxiliary audio and video outputs on one of the video conference end point devices that are being used to participate in a particular video conference session. The first technique is illustrated in FIG. 1.
A second technique uses an entirely different type of video conference equipment, which allows three or more participants to participate in a video conference without needing a multi-point control unit. This system connects the end point equipment of the various participants in a peer-to-peer style network, where each end point receives the video and audio data signals directly from each of the other end points. This is described as multi-tasking the video conference across the network. In this case, an IPTV client, which is a software application available from Cisco Systems, can be connected to the network to view the data packets of a video conference session as the data packets are passed back and forth between the actual end points participating in the video conference session. The IPTV client sits in the background and monitors all of the packets that are transmitted between the end points of the video conference session.
One advantage of the second system over the first technique is that the audio and video data signals stay in digital form. However, the IPTV client merely listens to the multi-task IP addresses. Thus, there is no centralized streaming server that is able to output a unicast multimedia data stream to a client. Rather, the IPTV client creates a multicast. However, multicasts generally cannot be received by most conventional local area or wide area networks that the video conference session has not originated on. Thus, this peer-to-peer system can only be used within a multi-cast capable network, such as a single local or wide area network. As a result, the IPTV client can only make the video conference data available to another IPTV client that is also on a multi-cast capable network.
The system shown in FIG. 1 accesses the digital video and audio signals of the video conference session output by a video conference end point device 60 through the analog output signals output by a video conference standard client 70. These analog output signals are also used to drive the audio and visual display devices used by the actual video conference participants. The system shown in FIG. 1 reconverts the audio signals back into digital data streams. As a result, the system shown in FIG. 1 can significantly degrade or otherwise distort the video and audio data.
Additionally, the video and audio data, which is originally in digital format, is converted to analog format and then reconverted to digital format. As a result, there is a significant delay between receiving the digital video and audio signals at the video conference end point device 60 and transmitting the re-encoded digital video and audio streams. The latency can be as long as 40 seconds. Finally, the system shown in FIG. 1 requires a physical connection between the video conference standard client 70 and a video capture encoding device 80 to transmit analog signals 72 and 74. As a result, each video capture encoding device 80 can be connected to at most one client 70.